The present invention relates to a rotor for an electric machine and also to an electric machine equipped with such a rotor.
Electric machines can be used for a wide range of purposes as a motor or as a generator. For example, electric synchronous machines with permanent excitation can be used in motor vehicles in order to drive said motor vehicles or in order to regenerate kinetic energy into electric energy when braking. An electric machine for this purpose generally has a rotor and a stator, wherein the rotor can rotate relative to the stator.
With a permanently excited electric machine, permanent magnets are mostly arranged on the rotor. Electromagnets, with the aid of which varying magnetic fields can be generated which alternate with the magnetic fields produced by the permanent magnets such that a torque is generated between the stator and the rotor, are located on the stator.
Since, during the rotation of the rotor, considerable centrifugal forces may act on the permanent magnets arranged on the rotor, these permanent magnets must be securely fastened on or in the rotor by means of suitable design features.
With a frequently used rotor type, a plurality of receiving spaces into which the permanent magnets can be initially inserted during assembly of the rotor and then fixed therein, for example by being glued or pressed in place, are provided within a rotor body. The receiving spaces are also referred to as magnet pockets and are located close to the outer periphery of the rotor body.
The rotor body preferably consists of magnetically soft material, such as iron. For example, the rotor can be formed as a disk set, in which a plurality of magnetic steel sheets are arranged as disks in succession in an axial direction. The magnetic steel sheets can be punched suitably into shape for this purpose, such that appropriate recesses for example are punched out therein and, when the disk set is assembled, form the receiving spaces of the rotor.
An exemplary embodiment of a rotor for an electric machine is described in U.S. Pat. No. 7,151,335 B2.